Mechanical stoker



Nov'. 23, 1937. J. A.- HOFFMAN MECHANICAL STOKER Filed May 29, 1934 5 Shets-Sheet 1 \3 vn w o w a@ o J l 00 o vl'.. \Ob O G L". Il O |\I i O .\\Pw l I l l ||l||l||||| SQ \N 00 QN] 00 -d lllll du. a on W Il id. Ilil- I .l -ll Illll WQ :L Ft

Nov.23, 1937. J. A'. Horl-FMAN MECHANICAL sToKER Filed May 29, 1954 5 Sheets-Sheet 2 m ww @mxl It l

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Nov. 23, -193.7. J A. HOFFMAN 2,100,252

MECHANI CAL STOKER Filed May 29, 1934 5- SheeS-Sheet 5 /za 16 fixa 1 6 I 3 kwa/Who@ :femme bffmm?,

J. A. HOFFMAN MECHANICAL sToKER Nov;- 23, 1937.

5 Sheets-Sheet 4 Filed May 29, 1934 ,l Jerome Hff Il Q :E Q |I man Nov. 23? 1937. 1A, HOFFMAN 2,100,252

MECHANICAL STOKER Filed May 29, 1934 5 Sheets-Sheet 5 gmc/MM Patented Nov. 23, 1&37

TATES PATENT OFFICE MECHANICAL STOKER f Applicationiuay 29,1934, serial No. 728,186

15 Claims.

This invention relates to mechanical stokers.

One object of the invention is to provide an automatic mechanical stoker constructed and arranged to uniformly feed fuel to a furnace, in which, in the present instance, air under pressure is supplied insuch a manner as to introduce secondary air over the fire to increase turbulence between the air and furnace gases to assist completion of combustion and to shield and protect the fuel distributing chamber and elements thereof and parts adjacent thereto from intense radiating heat of the furnace.

Another object of the invention resides in the provision of a mechanical stoker having a fuel distributing chamber which is protected from heat by conduction, convection or radiation from the furnace and which may be accomplished by the supply of air under pressure to the furnace to promote combustion and in a plane to shield the fuel delivery chamber and parts therein and adjacent 'thereto from detrimental heat attack from the furnace.

A still further object of the invention is to provide in a mechanical stoker, a fuel receiving section, a hollow supporting section, an intermediate fuel delivery casing forming a chamber section having communication with said other sections and embodying in the structure an auxiliary casing forming an air chamber associated with the intermediate fuel delivery chamber in such a manner as to tend to cool the fuel delivery chamber, from which auxiliary chamber, air under pressure is discharged to and through the hollow supporting section to the furnace to promote combustion as well as to promote the life of the delivery chamber casing and its mechanism by reason of protecting the same against intense heat from the furnace.

Another object of the invention resides in the provision of an effective, durable and economical mechanical stoker, embodying among other characteristics, means arranged to intercept and support particles of fuel falling by gravity and failing to pass to the furnace under the influence of the fuel delivery means and maintain such intercepted and supported fuel in the path of a stream of air under pressure and force of a character to sweep and carry such intercepted supported fuel to the furnace for consumption therein.

It is further designed to provide a mechanical stoker including a feeding means and means associated with the stoker structure for the supply of air under pressure to the furnace in such a manner as to prevent the extremely fine fuel from being precipitated over the dead plate of the furnace in amounts such as to overheat the dead plate and consequently create heat liable to attack the stoker.

I aim to prolong the life of mechanical stokers by preventing burning out or warping, or distortion of parts of the stoker incident to heat by radiation, convection, or conduction by the use of air under pressure and yet preheating the air to facilitate combustion of fuel as the air under pressure enters the furnace; and, if desired, I may associate with the stoker a water cooled heat absorbing device of suitable character to cooperate with the air supply to assist in protecting the stoker from a detrimental attacking heat from the furnace.

With these and other objects in View, the invention consists in the construction and novel combination and arrangement of parts hereinafter fully described, illustrated in the accompanying drawings and pointed out in the claims hereto appended, it being understood that various changes in the form, proportion and minor details of construction, within the scope of the claims, may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawingsz- Fig. 1 is a side elevation of a mechanical stoke embodying the present invention.

Fig. 2 is a front elevation of the mechanical stoker illustrated in Fig. 1.

Fig. 3 is a vertical longitudinal sectional View taken on the line 3-3 of Fig. 2, looking in the direction of the arrows.

Fig. 4 is a horizontal sectional view taken o the line 4-4 of Fig. 1, looking in the direction of the arrows. i

Fig. 5 isa view looking at the rear of the auxiliary casing removed from the stoker structure.

Fig. 6 is a plan view of the auxiliary casing removed from the stoker structure.

Fig. '7 is an end elevation of the auxiliary casing.

Fig. 8 is a vertical transverse sectional View on the line 8 8 of Fig. 5.

Fig. 9 is a fragmentary side elevation partly in section of a modified form of the invention.

Fig. -10 is a front view of the heat absorbing device arranged between thefurnace and the stoker in the modified form of invention illus trated in Fig. 9.

Referring now more particularlyl to the accompanying drawings, there is illustrated an automatic mechanical stoker, wherein A indicates generally, a casing on which is mounted a hopper I, secured thereon by means of a flange 2 and suitable fastenings 3 or in any other suitable manner.

The reference character 4 indicates a fuel feeding means arranged in the upper portion of the casing A and having communication at 5 with the hopper I. A suitable slidably reciprocating feeding means indicated, generally, by the reference character B is mounted in the fuel feeding section 4 and it may be of any suitable construction and arrangement but as shown it includes a lower portion 6 and a stepped portion 'l which portions Ii and l are slidable and connected in spaced relation with the stepped portion 'I above 1the lower portion 6 and with a feed opening 8 between the lower portion 6 and the stepped portion 'I as shown particularly in Fig. 3. 'Ihis particular character of feeding means B is not claimed herein and more detailed description would seem unnecessary with respect to the same, although it might be noted that the slide member 6 of the feeding means is adapted to slide on a suitable lining member 9 which is`replaceable in the event of wear and which in any event may or may not be employed but if employed will serve to protect the supporting means for' the slidable feed member 6 against undue wearing away of the respective part of the framework.

The feeding section 4 has communication `through a throat I0 with a fuel delivering casing including a chamber section II composed of the rearward and downwardly curved plate member I2 of the casing A and formed in part on its front by a frame member C including upper and lower horizontal frame members I3 andi I4, respectively, and a front curved Wall I5 which wall I5 is curved reversely with respect to the curvature of the. frame wall part I2. Thus, the upper portion of the fuel delivery chamber is cylindrically curved in cross section. The lower part or bottomof the delivery chamber II is formed by an auxiliary casing, indicated generally by the reference character D, which forms a removable and adjustable lip of the `fuel delivery chamber II. The auxiliary casing D is curved transversely and it has an air chamber, indicated generally, by= the reference character E, and a. shelf I 6 is carried by and projects from the rear wall of the air chamber. 'I'he shelf I6 may be eliminated if desired.

The auxiliary casing D includes end walls I 'I which are substantially segmental in shape and which extend upwardly from the ends of the air chamber E, the upper wall I8 of the air chamber chamber and including a transversely curved extension I9 which is adapted to bridge the space betweenY the front wall 20 of the air chamber E and the lower wall I4 of the frame member C and overlaps the front curved wall I5 of said frame member C. The curvature of the wall I8 and the extension I9 is reversed -with relation to. the curvature of the member I2 and corresponds substantially with the curvature ofthe wall I5 of the frame member C. The rear ofthe aux- 4 iliary casing D is spaced from the main casing vertical rear wall 22 which is provided with a relatively narrow longitudinal slot 23 with the inner face of the wall 22 beveled or flared forward, as at 24, to provide for a nozzled effect to project a curtain or blanket of air under pressure from the air chamber E in a manner and for a purpose to be hereinafter explained. The air chamber E and the air discharging slot 23 are of a length commensurate with the width of a fuel feeding opening of a furnace.

The transversely curved auxiliary casing D having the air chamber E and the forward extension wall I9 is removably and adjustably mounted in the enclosing casing A with relation to the upper cylindrically curved portion of the delivery chamber I I. The removable mounting of the auxiliary casing D'and its associated parts is for assembly purposes and the adjustment thereof is to provide for raising and lowering the rear portion or lip of the wall I8 of the auxiliary casing D to regulate and control the distance of throw of the fuel into the combustion chamber of a furnace.

lprovision of a pair of armsl, one at each end of the auxiliary casing D. These arms 28 are disposed below the under face of the wall I 4 of the frame member C and supported at their outer ends upon nuts 3I 'at the upper ends of screw bolts 29. The bolts 29 are for the purpose of supporting the auxiliary casing D threaded vertically through suitable brackets 3B on the enclosing casing A, scr that ,by rotating the screw bolts 29 in one direction, the arms 28 of the auxiliary casing are forcedupwardly to correspondingly shift the casing in an upward direction, while, upon rotating the screw bolts in the opposite direction,'the arms 28 can lower and the casing D can swing downwardly of its own weight plus the tendency thereof to swing downwardly due to the actionof the fuel feeding memberas hereinafter described. Each arm 28 has a terminal eye 32 at its inner end to receive a bolt 33. 'Ihe bolts 33 Ienter the respective screw threaded. sockets 34 formedA in the bosses 35 on the front face of the aforesaid extension wall I9 of the auxiliary 'casing D. v

By manipulation of the screw bolts 29, the lauxiliary casing D and its air chamber E and the extension wall I9 `may be adjusted to raise and lower the rear lip portion of the wall I8 of the auxiliary casing D for the purpose of controlling and regulating the height of the lip portion of the wall I8 to effectively control the feed of the fuel to the furnace. For instance, the higher the rear portion of the wall I 8, the farther into the furnace the fuel will be projected. Furnaces are so mounted and constructed as to demand such adjustments as to enable effective feed of the fuel to the furnace. Accordingly, by reason of my particular construction of and the mounting of the auxiliary casing D and its associated parts,

.portion of the wall extension I9 tting iiush with the curved wall I5 of the frame member C there is maintained such a tight fit between` the extension wall I9 and said curved wall I 5 as to preclude fuel finding its way between said walls.

The outer face of each end member II is provided with an arcuate groove 3B. These grooves 36 are guided over lugs 31 secured on the inner faces of the side walls 38 of the enclosing casing A whereby in removing the auxiliary casing D from the stoker with respect to the upper section of the main delivery casing the auxiliary casing D is readily swung to or swung outr of operative position according to the condition of the mounting and adjusting means. There may be times when it is desired to stiifen the connection between the auxiliary casing D and the frameA substantially equal to the length of the auxiliarychamber D and which projects forwardly from the front face of the wall extension I9. This plate 25 has slots 26 through which bolts 21 pass and enter t he wall I4 of the frame member C, effectively stiifening the connection of the auxiliary casing D to the frame member C.

Each end of the air chamber E is provided with a threaded opening 39 of relatively large size for the reception of a pipe 40 for the supply of air under pressure from any suitable source (not shown) for passage into the air chamber E and out of the same through the aforesaid slot 23. It is obvious pipe MJ must either be a flexible conduit or flexibly jointed to permit of adjustment of the casing D. The front wall of the air chamber E maybe provided with a screw All (Fig. 3) cui; off flush and positioned as illustrated for the purpose of providing for rigidity. This screw di is fitted in the lug l2 (Fig. 5).

A revolving delivery element indicated, genernally, by the character G is mounted in the delivery chamber section ll to rotate therein to throw or sweep the fuel off of the upper wall I8 of the auxiliary casing D through the throat 2l to and through the opening 43 of the hollow supporting section F into the furnace and over the entire grate area of the furnace.

The revolving delivery element G is mounted on a transverse shaft M which is journaled at its ends in water cooled bearings each including a casing 45, a water chamber 46 and a cylindrical bearing portion di in which Timken roller or other bearings d8 are arranged between the shaft and the bearing portions lll. Each bearing casing has an annular boss 48a at its inner end which rests on a seat t9 formed by a recess in the respective end wall il' of the casing D and through the bosses 48a and the bearing casings l5 the shaft fl rotates. Each bearing casing l5 also has an annular portion 35' which nts in an opening 95a of the respective side wall of the casing A, each casing d5 also having a flange 35h through the instrumentality of which end bolts d50 vthe bearings may be secured to the side walls of the casing 'A or otherwise mounted as may be desired. The water for cooling the bearing may be supplied from any suitable source by way of a pipe dtd and discharged by way of a pipe 56, as shownin Fig. 1 or in any other suitable manner.

The means for rotating this shaft dit is immaterial in so far as the present invention is concerned, but the shaft may be provided at one end with a. sprocket wheel 5B, conned by a lock nut 5l, to receive a drive chain (not shown) for driving purposes.

A group of spreading blades H is mounted on the shaft dfi to swing, due to rotation of the shaft dll. Each blade H consists of a rigid tapered arm 52 and a blade 53 rigidly connected to the respective arm. The blade portions of the spreading elements are relatively thick and heavy and the blade portions extend lengthwise parallel to the shaft lill and have their outer faces curved, as at 52' with their fuel striking faces provided with curved flanges 53. The described shape of the blades H is such as to promote a sweeping action of these blades over the bottom portion of the delivery chamber ll so as to uniformly spread the fuel and effectively throw or sweep such fuel out of the chamber through the feed throat 2l, as well as forcibly discharge the same rearwardly through the opening d3 of the supporting section F while at vthe same time spreading the same uniformly over the entire grate area of the furnace.

The group of blades H are arranged in spaced sets of four blades to each set, as may be gathered by reference to Figs. 3 and 4. The blades of each set are swingingly mounted on a transversely disposed pintle 54 which passes through the hubs 55 of the respective blades H and through spacing elements 56 fastened by keys 5l to the shaft 44, as shown particularly in Figs. 3 and 4. The ends Il of the auxiliary casing D are cut away on theinner faces, as at 58, to accommodate the end spacing elements 56, as shown in Figs. 4 and 8, the end spacing elements fitting close to the inner ends of the aforesaid bearing casings 45. As the shaft lll rotates, the spacing elements 56 being secured thereto, vand the blades H being swingingly mounted on the pintles 54, it is clear that rotation of the shaft i4 effects such action as to effect an outward swing and rotative movement of the blades H which swing at a speed according to the speed of rotation of the shaft it and at all times at such speed of rotation as to cause the blades H to effectively act upon the fuel delivered to the delivery chamber l l toV force the fuel from the delivery chamber H.

The enlarged outer ends of the blades facilitate the centrifugal action thereof and when the shaft IM is in action it is clear that there is a powerful driving movement given to the blades H as they move around the delivery chamber Il effecting a positive discharge of fuel from said chamber. It will thus be understood that the blades are not rigidly held to the shaft tl but that they have swinging connection there'- with through the spacing elements 56 and the pintles 54 and that by virtue of this particular mounting of the blades if an obstruction should occur there will be no danger of breakage of the blades or their mountings because of their capability of giving incident to their pivotal mountings. The speed of rotative movement of the blades H ordinarily remains constant with the degree of rotation of the shaft lll and it will be seen that by virtue of the particular mounting of the blades, they and the shaft lil and the bearings do not have to be independently adjusted upon adjustment of the auxiliary casing D.

The stoker supporting section F is located in the lower rear portion of the main casing A, and is shown as constituting a chamber, (see particularly Fig. 3) and this chamber is formed by the furnace attaching plate 59, side walls which are rearward, downward extensions of the side walls of the main casing A, a bottom wall 6U integral with said side walls at their lower ends and a door or closure composed of a baffle plate 6i and an outer plate 62 secured together in spaced relation by the spacing elements 63 and bolts Gd. The baffle plate 6l has Ventilating apertures 65, as shown and the outer plate 62 has Ventilating openings 66 and the side walls of the section F may have Ventilating perforations 66 and it will be understood that the attaching plate 59 is of.size depending upon the size of the furnace opening and that this plate 59 is secured to the casing A, say for instance, at 61, by welding or otherwise and that it has openings 68 by means of which it may be secured to the front of the furnace over the iire box fuel inlet opening.

The door lil-62 is preferably hingedly mounted by means of a suitable pintle 69 and provided with any common form of latch '10. By virtue of this door 6I--62 access is readily had to the interior of the section F for cleaning or other purposes. c

The stoker described is relatively small and compact with., the result that the supporting section F is relatively narrow but in the event that the fuel delivery mechanism should fail to throw or feed all of the fuel through the opening 43 of the supporting section, that is to say, if some of the particles of fuel should fall by gravity as it passes through the throat ZI on the way to the opening 43, such particles falling by gravity would ordinarily go to the bottom of the hollow supporting section F. To prevent this and to conserve fuel and to insure practically all of the fuel discharged from the delivery chamber il to go to the furnace, I provide the aforesaid shelf i6 which intercepts and supports temporarily at least such particles of fuel as fall by gravity between the throat 2I of the delivery chamber II and the opening 43. This shelf I6 may be provided with end plates 'II formed therewith or welded thereto and the shelf I6 and its ends 'III project from the rear wall of the air chamber E and are preferably welded to the rear wall of the air chamber E with the shelf I6 slightly below the air discharge nozzle 23--24 of the air chamber E so that the air under pressure issuing through the air nozzle 23-24 will effectively sweep the shelf I6 and carry particles of fuel thereon through the opening 43 of the supporting section F into the furnace.

The air under pressure issuing from the air chamber E is in the form of a curtain or blanket and of a width substantially the width of the opening 43 of the hollow supporting section F and of the fuel receiving opening leading into the furnace, to introduce secondary air over the re to increase turbulence between the air and furnace gases, thus assisting completion of combustion. This curtain or blast of air spreads the extremely fine coal over the burning fuel on the grate of the furnace, preventing the ne fuel from being precipitated over the dead plate of the furnace in amounts that would have a bad effect, due to overheating the dead plate and consequently the stoker parts. This air under pressure protects and shields the fuel delivery chamber II and the blades from the intensity of the heat of the furnace, thereby preserving the life of the chamber II and the parts associated therewith and parts adjacent thereto. Of course there is some heat applied to the chamber I I and the blades H and parts in close proximity thereto but the curtain or blanket of air modifies the heat to such an extent as to prevent distortion of the front portion of the bottom of the delivery chamber II as well as preventing burning out of parts and yet preheats the air of the air chamber E to facilitate combustion of fuel as the air under pressure enters the furnace.

The curtain or blanket of air hasa tendency to prevent noxious gases from leaving the furnace under a balanced draft condition and working back into the stoker and out therethrough to the4 ing section 4 receives fuel from the hopper I, the reciprocation of thereciprocating means 6'-1 brings about feed of the fuel in regulated quantities through the throat IIJ to the delivery chamber II. From chamber II the fuel is discharged in regulated uniform quantities through the supporting section F to the furnace and while such a structure, broadly speaking, may not in itself be new, the invention concerned in the present case results in a` more effective utilization of such elements by reason of the new features herein described in connection with the fuel delivery chamber II and the auxiliary casing c ntaining the air chamber associated therewith a Well asthe means for intercepting fuel ordinarily precipitated on the dead plate and not on the effective grate area of the furnace.

It would seem unnecessary to describe the manner in which the reciprocating feeding means 6-1 is operated as this feeding means forms no part of the present invention. Suffice it to say that the feeding means and the revolving spreader mechanism are operated in timed relation in a manner as may be common in mechanical stokers of the present character.

In another embodiment of the invention and with the thought in mind to further protect the stoker from attack by heat radiating from the furnace, and as illustrated in Figs. 9 and 10, I

may interpose a water cooled heat absorbing device 72 between the furnace shown in part at 'i3 and the Stoker comprising a frame including front and rear plates 'i4 and 'I5 which are maintained in spaced relation by inner and outer sets of spaced metal strips l5 and Tl, respectively, which are welded to or. otherwise secured to the inner faces of the plates 'lil and l5 in a manner to provide water tight joints and to provide a water channel i8 having a water inlet 'I9 and a water outlet 8U. Bosses 8l and 82 are welded or otherwise secured to the front plate l@ and have screw threaded openings which align with the inlet and outlet openings l@ and til, respectively,

Aand in which screw openings of said bosses pipes (not shown) may be secured to supply Water under pressure to the channel it for continuous circulation through the channel. The assembled plates have an opening 233 centrally thereof and this opening is adapted to align with the discharge opening 64 in the supporting section 85 of the stoker and with the re box or combustion chamber fuel receiving opening 66 of the furnace.

The heat absorbing device frame may be other than the rectangular shape shown as may lalso: the central opening 83. The assembled frame of the water cooled heat absorbing device 'I2 is prefc erably provided with open ended sleeves or the like 81 welded to the plates ill and l5, as indicated at 88 and open outwardly through said plates to provide holes to receive bolts or the like 89 adapted to be passed through holes 9b in the wall 9| of the supporting section of the stoker and into the front wall of the furnace as shown in Fig. 9. This type of heat absorbing device is more specifically described in a co-pending application filed by me on the 29th day of May, 1934 Serial Number '728,184 and is not claimed herein except as to combination thereof with other elements. The heat absorbing device may be positioned and held in place between the stoker and the furnace in any suitable manner. As cool water continuously enters the device at the inlet point thereof and bythe partition 92 in the water channel is forced to circulate upwardly and around the channel to the outlet point of the device, heat radiating from the furnace is absorbed by the water in the water channel and carried away from the stoker, protecting the latter from 1. A mechanical stoker including fuel receiving means and a fuel delivery means comprising a main casing including an upper cylindrically curved portion and a lower transversely curved auxiliary casing cooperating with said cylindrically curved portion to form a fuel deliverychamber, a rotary fuel feeding member therein, said auxiliary casing containing an air chamber, the upper wall of the auxiliary casing constituting the lower wall of said main casing, the rear wall of said auxiliary casing being spaced from the rear wall of the upper cylindrically curved portion of said main "casing to provide a fuel delivery opening leading from said fuel delivery chamber, the auxiliary air chamber casing having an air discharge opening at the rear thereof below said fuel delivery opening.

2. A mechanical stoker including fuel receiving means and a fuel delivery means comprising a main casing' including an upper cylindrically curved portion and a lower transversely curved auxiliary casing cooperating with said cylindrically curved portion to form a fuel delivery chamber, a rotary fuel feeding member therein, said auxiliary casing containing an air chamber belowthe fuel delivery chamber of an area extending under a substantial area of the lower portion of the fuel delivery chamber, the upper wall of the auxiliary casing constituting a substantial part of the lower wall portion of said main casing, the rear wall of said auxiliary casing being spaced from the rear wall of the upper cylindrically curved portion of said main casing to provide a fuel delivery opening leading from said fuel delivery chamber, the auxiliaryr air chamber casing having an air discharge opening at the rear thereof below said fuel delivery opening and extending substantially throughout the length of the auxiliary casing.

3. A mechanical stoker including fuel receiving means and a fuel delivery means comprising a main casing including an upper cylindrically curved portion and a lower transversely curved auxiliary casing cooperating with said cylindricallycurved portion to form a fuel delivery chambei', a rotary fuel feeding member therein, said auxiliary casing containing an air chamber, the upper wall of the auxiliary casing constituting the lower4 wall of said main casing, the rear wall of said auxiliary casing being spaced from the rear wall of the upper cylindrically curved portion of said main casing to provide a fuel delivery opening leading from said fuel delivery chamber, the auxiliary air chamber. casing having an air discharge opening at the rear thereof below said fuel `delivery opening, and means for supplying air under pressure to said air chamberfor passage through the latter to cool the lower wall portion of the main casing.

4. A mechanical Stoker including fuel receiving means and a fuel delivery means comprising a main casing including an upper cylindrically curved portion and a lower transversely curved auxiliary casing containing an air chamber cooperating with said cylindrically curved portion to form a fuel delivery chamber, a rotary fuel feeding member therein, `the upper wall of said auxiliary casing constituting the lower ywall portion of the main casing, said upper wall of the auxiliary casing including a transversely curved extension extending forwardly and upwardly into the upper portion of the cylindrically curved portion of the main casing and overlapping the front wall of the latter, the rear wall of said auxiliary casing being spaced from the rear wall of the upper cylindrically curved portion of the main casing to provide a fuel delivery opening leading from said fuel deli ery chamber, the auxiliary air chamber casing having an air discharge opening in the rear wall thereof below said fuel delivery opening.

5. A mechanical stoker comprising an enclosing casing having fuel receiving means and including sides having inwardly-directed oppositely-disposed lugs, a fuel delivery casing including an upper cylindrically curved portion, and a lower transversely curved auxiliary casing cooperating with the upper cylindrically curved portion to form a fuel delivery chamber, a rotary fuel feeding member therein, said auxiliary casing having upper and lower spaced apart walls forming an air chamber therebetween having an air inlet and outlet, the said outlet being open through the rear wall of the said casing, the upper wall of the aux' iliary casing constituting the lower wall portion of said fuel delivery chamber, said upper wall of the auxiliary casing having a transversely curved extension extending forwardly and upwardly into the upper portion of the cylindrically curved portion of the fuel delivery chamber in engagement with the inner face of the upper front wall of the latter, the rear wall of said auxiliary casing being spaced from the rear wall of the upper cylindrically curved portion of the fuel delivery chamber forming a rear delivery opening from the delivery chamber through which fuel is discharged by said fuel feeding member, the ends of the auxiliary casing extending above the upper wall of the auxiliary casing within the sides of said enclosing casing and having curved grooves on their outer faces which slidably embrace the aforesaid lugs on the inner faces of the sides of the enclosing casing as the auxiliary casing is positioned in the enclosing casing or removed therefrom, and means for seeming the auxiliary casing in operative position in the enclosing casing and in cooperative relation with the said cylindrically curved portion of the delivery chamber casing..

6. A mechanical stoker comprising an enclosing casing having fuel receiving means and including sides, a fuel delivery casing including an upper cylindrically curved portion, and a lower transversely curved auxiliary casing cooperating with the upper cylindrically curved portion to form a fuel delivery chamber, a rotary fuel feeding member therein, said auxiliary casing having upper and lower spaced apart walls forming an air chamber therebetween having an air inlet and outlet, the said outlet being open through the rear wall of the said casing, the upper wall of the auxiliary casing constituting the lower wall portion of said fuel delivery chamber, said upper wall of the auxiliary casing having a transversely curved extension extending forwardly and upwardly into the upper portion of the cylindrically curved portion of the fuel delivery chamber in engagement with the inner face of the upper front wall of the latter, the rear wall of said auxiliary casing .being spaced from the rear wall of the upper'cylindrically curved portion of the fuel delivery chamber forming a rear delivery opening from the delivery chamber through which fuel is discharged by said fuel feeding member, cooperative connecting means between the ends of the auxiliary casing and the sides of the enclosing casing for guiding the auxiliary casing into and out of operative position with relation to the upper cylindrically curved portion of the delivery chamber casing, and means for adjustably fastening the auxiliary casing in operative position with relation to the upper cylndrically curved portion of the delivery chamber casing.

7. A mechanical stoker including fuel receiving means and a fuel delivery means comprising a casing including an upper cylindrically curved portion and a lower transversely curved auxiliary casing cooperating with the upper cylindrically curved portion to form a fuel delivery chamber, a rotary fuel feeding member in said chamber, said auxiliary casing containing an air chamber, the upper wall of which constitutes the lower wall of said fuel delivery chamber, the/air chamber having an air inlet and a narrow air outlet of a length substantially the length of the air chamber, and means whereby to supply air under pressure to the air chamber and force a curtain or a blanket of air through said air discharge opening.

8. In a mechanical stoker,'a casing having fuel receiving means and including sides and a fuel delivery chamber having a fuel outlet composed in part of an internal substantially segmentalshaped combined apron and air chamber including end portions and upper and lower walls forming between them an air chamber, the upper wall of the combined apron and air chamber constituting the lower wall of the delivery chamber, said air chamber having a discharge outlet, the sides of the casing having oppositely disposed bearing openings therein and the end portions of the substantially segmental-shaped combined apron and air chamber having oppositely disposed openings of smaller diameter than said bearing openings and aligning therewith, watercooled bearings each including a water-jacketed casing having its inner end mounted in said side bearing openings and having its inner end reduced in diameter and tted in the respective opening of said end portions of the substantially segmental-shaped combined apron and air chamber, a driven shaft extending transversely of the casing adjacent to the combined apron and air chamber and having its ends journalled in the respective water-cooled bearings, a fuel feeding member on said shaft for discharging fuel through said fuel outlet, means for circulating water through said water-cooled bearings, and, means for supplying air under pressure to said air chamber for discharge under pressure through the discharge. outlet of the latter.

9. A mechanical stoker including fuel receiving means and a fuel delivery means comprising a main casing including an upper cylindrically curved portion and a lower transversely curved auxiliary casing cooperating with said cylindrically curved portion to form a fuel delivery chamber, a rotary fuel feeding member therein, said auxiliary casing containing an air chamber, the upper wall of which constitutes the lower wall of said main casing, means for adjustably mounting the lower transversely curved auxiliary casing in position with relation to the upper cylindrically curved portion of the main casing, means for stiffening the contacting parts of the auxiliary casing and the upper cylindrically curved portion of the main casing after an adjustment has been effected, the air chamber having a discharge outlet and also having an air inlet whereby air may be supplied to the air chamber to cool the lower transversely curved auxiliary casing and become preheated for discharge through the discharge outlet of the air chamber.

10'. A delivering mechanism for a stoker includinga casing having a fuel inlet and a fuel outlet, means in said casing for distributing and discharging fuel through said outlet, said casing including a lower portion having a discharge shelf and a chamber for the passage of cooling air through the same to cool the delivering mechanism, said chamber having a discharge opening above the shelf, and said lower portion of the casing being bodily adjustable to vary the inclination of the said shelf and the discharging air stream.

11. A delivering mechanism for a stoker lncluding a casing having a fuel inlet and a fuel outlet, means in said casing for distributing and dischargingfuel through said outlet, said casing including a lower adjustable portion having a chamber for the passage of air therethrough under pressure to cool said lower adjustable portion, said lower adjustable portion having a discharge shelf and an air outlet from said chamber above said shelf, and means for adjusting said lower casing portion and holding the same in adjusted position.

12. A delivering mechanism for a stoker including a casing having a fuel inlet and a fuel outlet, means `in said casing for distributing and discharging fuel through said fuel outlet, said casing having a lower adjustable portion forming at its rear the lower edge of the fuel outlet and having a chamber provided with an air lmet for the circulation of air to cool the same, said chamber having a rear outlet, adjacent to and below vthe fuel outlet for the discharge of a stream of air with the discharging fuel, and means to adjust the said lower portion of the delivery casing to thus vary the inclination of the discharging air stream.

13. The combination with a furnace having a fuel receiving opening, of a Stoker comprising a fuel receiving and distributing mechanism including a casing anda distributing member therein, the casing having an inlet and also having an outlet at the rear end thereof, said outlet being arranged adjacent the fuel receiving opening of the furnace and cooperating therewith to provide a fuel delivery passage between the rear end of thestoker and the furnace, said casing having a lower hollow portion forming an air chamber at the lower portion thereof to receive air under pressure, the air chamber having a relatively long opening in the rear thereof for the supplyof a curtain'of ail; under pressure from said air chamber through said relatively long outlet opening thereof to the furnace through said passage at the lfuel receiving opening of the furnace and the outlet opening of said casing to assist in the distribution of the fuel and' to assist combustion of fuel in the furnace 'and to protect said casing from detrimental attacking intense heat from the furnace, and a water-cooled heat absorbing device arranged between the furnace fuel receiving opening and the rear outlet of the fuel distributing casing and having an opening alined with the discharge outlet of said casing and the fuel receiving opening of the furnace to cooperate with the said curtain of air to assist in protecting the Stoker casing from attack by the intensity of the heat from the furnace.

14. The combination with a mechanical stoker and a furnace provided with a fuel receiving opening, ofa delivery mechanism associated with the stoker including a casing having a fuel inlet and a fuel outlet, an impeur mechanism in said casing for distributing and discharging fuel from said casing through said fuel outlet into the fur- Y nace, said casing having a lower portion forming at its rear the lower edgeof the fuel outlet and having a chamber under the impeller mechanism provided with an air inlet for the reception of air under pressure to cool the casing beneath the impeller mechanism, said lower portion of the casing being adjustable to vary the inclination of the said lower edge of the fuel outlet, said chamber having a relatively long rear outlet adjacent to and below said fuel outlet for the discharge of a curtain of air under pressure from said chamber of a width substantially the same as the width ofv the furnace fuel receiving opening simultaneously with the supply of fuel to the furnace to spread the fuel over the burning fuel in the furnace and to assist combustion in the furnace and to shield the impeller mechanism casing and the interior thereof from the intense heat of the furnace by modification of the heated products of the furnace issuing from the fuel opening of the furnace toward the said casing.

15. The combination with a furnace having a fuel receiving opening, of a stoker provided with a fuel receiving and distributing mechanism including a casing having a fuel outlet at the rear thereof coinciding with the fuel receiving opening of the furnace for the passage of fuel from thei fuel receivingand distributing mechanism casing into the furnace, said casing carrying an air chamber at the lower portion thereof to receive air under pressure to cool the interior of said casing and having an outlet inthe rear wall of said chamber extending across the fuel receiving opening of the furnace to supply a curtain of air to the furnace under pressure from the air chamber through the outlet of the latter and through said fuel receiving opening, and a water-cooled heat absorbing device arranged between the front of the furnace andthe rear of the stoker and having an opening alined with the outlet opening of said fuel receiving and distributing casing and the fuel receiving opening of the furnace and through which said curtain of air under pressure passes, the curtain of air entering the furnace assisting combustion and also cooperating with said air chamber to protect the interior of t-he fuel receiving and distributing chamber and parts adjacent thereto from attack by the intenseheat of the furnace.

JEROME A. HOFFMAN. 

